The long term objective of this research is to explain the mechanism of insulin action in the human body in order t contribute towards improvement of clinical treatmend of diabetes. The specific objectives ofthe propoedstudy are to elucidate the mechanism by which the hormone stimulates the specific hormones receptor in the cell membranes and thereby induces characteristic regulatory effects on the "insulin-sensitive" reactions, such as the adenylate cyclase-phosphodiesterase system, which is also located in the cell membrane. First, the insslin-binding activity and the adenylate cyclase-phosphodiesterase cystem will be obtained in an isolated cell membrane fraction. Subsequently, attempts will be made to link functionally the receptor an the enzyme activities in a cell-free sytem. When the coupling of the two activities is achieved, th system will be used for the further purification and characterization of the insulin receptor and for the study of the mechanism of insulin action at the molecular level.